Other expected guests are Leigh Gallagher, who has drawn for the Lego Bionicle comics and also DC Comics' The Witching and Justice League Unlimited.

It is hoped Lee Carter, who has worked on games titles such as Project Gotham Racer, and Asia Alfasi, a Manga comic writer and artist who was born in Libya but moved to Scotland as a child, will also attend.

A children's competition for original comic art was launched in November to tie in with the convention.

Mr Clements said the second year of the event could determine whether it becomes a permanent fixture.

Held in Eden Court Theatre, some guests for the inaugural 2008 event were unable to attend because of bad weather. However, many of those who did make it agreed to appear again.

The convention will run just days before the US and UK releases of the Watchmen movie.

While the graphic novel has had a cult following, hype surrounding the film has been building with its characters appearing on the cover of Empire film magazine.

Hollywood director Zack Snyder has promised his adaptation will be faithful to its source.

Presenting three excerpts from his forthcoming film at a press event in London in November, he said he wanted to give audiences the "quintessential" Watchmen experience.

Dave Gibbons, who drew the illustrations for the original 1987 comic, said Moore had previously had "bad experiences" with Hollywood.

Previous adaptations of the writer's work include The Extraordinary League of Gentlemen, which starred Sean Connery, and From Hell, which had Johnny Depp in the lead role as a clairvoyant detective investigating murders by Jack The Ripper.

Snyder, who directed the 2004 remake of zombie horror Dawn of the Dead and the 2006 movie 300, said he was "disappointed" by Moore's decision but respected his wishes.

Set in an alternate version of 1980s America, Watchmen imagines a parallel universe where masked heroes and crime-fighting vigilantes are commonplace.

Only one, though, has super powers - the luminous Dr Manhattan, a scientist who acquired god-like abilities after a laboratory accident.

COMICS FACT FILE

Large comic book conventions are held in Bristol, Birmingham and Leeds. In Scotland, there is Prestonpandemonium at Prestonpans, near Edinburgh, and an event dedicated to Japanese Manga and Anime has been held in Glasgow.

The Beano, Oor Wullie and The Broons are among Scotland's best-known comics and cartoon strips.

Scotland can also draw links to the graphic novels on Bran Mak Morn - a fictional king of the Picts - and 200AD comic's mutant bounty hunters, the Strontium Dogs. The village of Strontian in Ardnamurchan is close to where strontium was found in the mineral strontianite.

Mr Clements said: "The Watchmen film will be a big event.

"It is likely to be the subject of debate at Hi-Ex with John Higgins and Alan Moore's daughter Leah - a writer in her own right - coming up.

"I have seen the trailer and it looks extraordinary.

"The book is so dense. I've read it 20 times and each time I see something I didn't notice before - there are so many layers to it. If the film manages to deal with a 10th of it, it's doing well."

The convention organiser said themes tackled in Watchmen were relevant to today's troubled times and conflicts in Afghanistan and Iraq.

He said: "Watchmen was written during the 80s and is a Cold War book. With the politics of today and the War on Terror, it's as if nothing has changed since it was written."

One of the characters, The Comedian, whose murder is one of the key storylines of the graphic novel, fought in the Vietnam War.

Comparisons are often drawn between that war and today's conflicts.

Meanwhile, zombies could be another theme at Hi-Ex.

Mr Clements said: "I am thinking about doing something on zombies, there seems to be a huge market and they seem huge at the moment.

"Leigh Gallagher, one of our guests, has drawn 17th Century zombies for the comic 2000AD."

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